6.9 Transmission Upgrade

[Oversize]

The only question with that config is what final drive to use....

 

[motec 6.9]

Are you paying attention box can take 1000Nm because it needs to handle the S65 which is limited to 1000Nm. With 5 speed and gearvendors 10 speed so it could be called Malvern Star.

 

[Oversize]

Yes but how much would that all cost by the time you get the trans, overhaul it, buy a GV, modify it to fit (at both ends), plus buy an ECU?

 

[Oversize]

What diff ratios do Quaife offer?

 

[Oversize]

Here's the link but no word on ratios:

http://shop.quaife.co.uk/quaife-mercedes-limited-slip-diff-kit-for-sel-class-116-450-se-450-sel

 

[motec 6.9]

ECU is $900 adapting is a lot less than Franz wants for rest of the parts to fit Turbo 700 . Quaife is available in what ratio you require. If going Mb 5 speed I was going to go with 3.46 diff centre ratio. Trans rebuild is about the same as most 4 to 6 speeds from US as that is were current stock comes from. And seeing as its used by Chrysler there are upgrades out there same box is known as NAG1 which means New Age Gearbox 1 . Already been adding up that's why I went to see Torque Fabrications in the first place.

 

[motec 6.9]

Ok Mark this is what I am talking about http://www.moparmax.com/tech/2012/vii_12-transmission-1.html http://www.shophemi.com/c-1154-automatic-transmissions.aspx . Its cheaper to buy upgraded trans from US and as I said Chrysler hot up boys have jumped on board so price and stronger parts are being made. Bell housing only difference and it unbolts .

 

[Styria]

What an excellent and informative post. Regards. Styria

 

[motec 6.9]

Now I no I can buy the transmission and I can get it fitted and buy cpu. Just need to allocate the funds to do so.

 

[motec 6.9]

Hi Mark see post about built boxes upto and above 1000hp rated only bell housing is different and that unbolts.

 

[Oversize]

At a guess I'd say the mods of MB 5sp, ECU, GV OD, custom bellhousing and driveshaft, plus Quaif diff would not leave any change from $14K! Ouch!

 

[motec 6.9]

Wouldn't need Gearvendors with 5 speed thinks around 5k possible. Check price from states.

 

[motec 6.9]

http://www.shophemi.com/c-1154-automatic-transmissions.aspx start just over 2600 rebuilt out right price.

 

[Oversize]

This is the only Mb box of any interest
5G-Tronic (W5A580/Large NAG)[3]1st 3.588 2nd 2.186 3rd 1.405 4th 1.000 5th 0.831 -3.167 -1.93
However, all V12-powered cars such as the S600 and S65 AMG still retain the 5G-Tronic, which has a torque capacity of 796 lb-ft

Wiki lists another 5 speed and I'm wondering what's the difference? It seems to have better ratios than the large one:

5G-Tronic (W5A330/Small NAG)

3.951 2.423 1.486 1.000 0.833 -3.147 -1.93

 

[Oversize]

I like the ratios of the GM 6180E 6 speed (rated to 720Nm), and the bell housing is also removable. However this box and the MB 5 speed both house the oil galleries for the front pumps in the bell housing, so it's not as straightforward as just bolting on a modified bell for the M100 pattern. Not sure if there's a stand-alone ECU available for the GM box either. More research is needed before a decent solution is found. Strange the MB 5 speed has 2 reverse gears!

 

[Oversize]

The answer is yes there is an ECU for the GM trans:

http://www.zerogravityperformance.c...ic-transmission-controller-6l80e-6l90e-6l50e/

The bell housing issue is still a significant one yet to be overcome. You'd probably need an adapter built with the aid of a CNC machine. Or somehow grafting on a 6.9 bell housing although that idea doesn't sound appealing!

 

[Styria]

I have looked at this thread in detail again, but am not sure where it is leading to. There is no doubt that, for faster acceleration from standstill, plus lower revolutions in top gear for more relaxed cruising on the open road, it would be nice to have a more versatile box than fitted in the 6.9s by the factory.

First of all, regarding 6.9 torque. Unless one wants to be brutal, the standard box, as is, is quite capable of handling the torque output. After all, it is essentially a VERY similar box to the one that's fitted to the 450s and so obviously Mercedes did not bother to go to any great lengths in strengthening the box. I have on hand a fully rebuilt 126-500SEL differential that runs a ratio of about 2.45:1. If I was to fit that final drive to my Gleaming Beauty, it would obviously benefit by having a higher final speed per 1000rpm. As it is, Gleaming Beauty achieves just on 40 km/hour in top gear, and maximum torque by the high compression engine of 3000 rpm takes you up to 120 km/hour. I'd be satisfied with that, especially if the 2.45 ratio diff. produces how many more kilometres compared with standard.

That only leaves the high first gear good for 105 kms/hour. I almost feel that faster acceleration from standstill is only of academic value - perhaps for the first 50-80 meters or so. After that, let them catch you if they can - or, more appropriately, can you catch after they're gone - maybe not. I find that with the exhaust system fitted to GB, I have already attained an additional 5% in acceleration, although it feels almost more than that. I should put the stop watch on GB, although there is every chance that one could get pinged by the men in Blue. Interested in more opinions. Regards Styria

 

[Oversize]

People have always complained about the standard trans and it's one of the reasons the earlier 6.3 was (slightly) faster 0-100. The 6.9 box had a very tall first gear, which works against good acceleration times.

The 126 boxes lack an overdrive for lower fuel consumption and an even higher top speed. The 126 box cannot cope with the torque from the M100 either so it's not the right choice. A GV add on unit is too costly, too bulky and too heavy.

So that leaves us with a later box to consider. Don't worry I'm on the case! A chance meeting at Motorex has me wanting to know much more! Stay tuned....

 

[Oversize]

The diffs are a separate matter and the 6.9 uses a 2.65 ratio. The 6.3 used a 2.85 which is another reason for its 0-100 ability. The higher number means quicker acceleration, but a lower top speed.

FYI the Euro 560 and W140 600SEL use the same ratio as the 6.9.

The Veyron uses a shorter (lower) ratio 3.64, as does the VE SSV at 2.92. The reason these cars can use such a ratio to achieve fast acceleration time, PLUS achieve high top speeds is the fact both have 2 overdrive gears. The Veyron also benefits from loads of power, high tech aero and high speed tyres.

Ratios explained:
http://www.badasscars.com/index.cfm...ct_id=398/category_id=13/mode=prod/prd398.htm

 

[c107]

People have always complained about the standard trans and it's one of the reasons the earlier 6.3 was (slightly) faster 0-100. The 6.9 box had a very tall first gear, which works against good acceleration times.

The 126 boxes lack an overdrive for lower fuel consumption and an even higher top speed. The 126 box cannot cope with the torque from the M100 either so it's not the right choice. A GV add on unit is too costly, too bulky and too heavy.

So that leaves us with a later box to consider. Don't worry I'm on the case! A chance meeting at Motorex has me wanting to know much more! Stay tuned....

Has anyone ever looked at combining a 450 rear end with a separate overdrive unit? That would make 1st gear more usable but at the same time give the overdrive gear that is needed.

I watched one of the Jay leno videos a few years ago and he fitted an overdrive to a 426 hemi so if it can handle that i'm sure a 6.9 would be fine.